NART.

My conviction about God's love has a few different sources; namely experience, Bible, external evidence, and the experience of others. Any experiences I cite of my own are both unprovable and irrefutable, since they are my personal experiences and can't convince any of you. I can say I know that I've experienced the presence of God in his love and there's no calling it one way or the other, it is completely personal.
The Bible is a bit trickier because there are two components. Is it a historically accurate document and is it telling the truth? I believe it is a historically accurate document. We have more copies of early manuscripts of the Bible than we do of almost any other historically accepted document. I find the teachings in the Bible, particularly the New Testament which fulfilled the Old and created a new way of living for God's people, to be worthwhile and consistant with real life. The principals in it are good, which is the way most people choose their religions, and it describes a spiritual material world view that I find to be practical and consistant with logic (read Mere Christianity by C.S. Lewis). Again, experience plays into this because my experience confirms what is presented as truth about God in the Bible.
External evidence. This is basically the principals of the Bible enacted and operating in real life and how well they fit into the world. As I said, I find them to be worthwhile and promoting helpful, healthful interactions between people. I conclude that God designed the world to work a certain way and when we follow the way that he, in his love, designed for us, things work better. More about external evidence but it's 12:30 and I'm too incoherent to put it down.
The experience of others is, again, unprovable one way or the other, but when I am talking to people I trust and have found them to be honest, practical, and so on in other matters of their life, I tend to consider what they say with more belief than I would if they decieved me.
God's love is something I have experienced, learned about, witnessed operating in the world, and seen in others.
Would I marry someone that displayed their love the same way as God displays his love? Too tall an order for a human. I don't see how you can experience such love and not desire to love entirely in return so I would probably attempt to do whatever pleases that person, as I attempt (keyword: attempt) to do whatever pleases God in return for his absolute love for me and everyone in the world. God gave more than anyone else can ever give, in demonstrating his love.
Boy I get wordy when I'm tired.